Multiple compressible lampholder



g- 8, 1961 J. M. PXSTEY 2,995,722

MULTIPLE COMPRESSIBLE LAMPHOLDER Filed Dec. 2, 1957 if g M of w ///s flffo/wqg/ 2,995,722 MULTIPLE COMPRESSIBLE LAMPHOLDER John M. Pistey, Fairfieid, Conn, assignor to General Electric Company, a corporation of New York Filed Dec. 2, 1957, Ser. No. 700,113 7 Claims. (Cl. 339- 51) The present invention relates to fluorescent lampholders and particularly those used for supporting one end of a bank of two or more fluorescent lamps.

Multiple fluorescent lampholders are quite popular at the present time. Most, if not all, of such lampholders have been made for years with metal housings comprising a hollow base and a back cover plate. Compressible discs of insulating material have been located in openings in the front face of the base for supporting and carrying electrical contacts to engage the terminals of the lamps. A serious difficulty that has always plagued this type of lampholder is in the corrosion of the metal housing in locations having extreme atmospheric conditions, whether it be in chemical plants, paper and textile mills or refrigerated rooms where the corrosion of the metal is accelerated.

The principal object of this invention is to provide a fluorescent lampholder with a compressible lamp-receiving disc that has a novel guiding and spring-biasing means.

A further object of this invention is to provide a novel chamber for receiving the compressible disc whereby the disc will have a straight line reciprocating motion.

A still further object of this invention is to provide a multiple fluorescent lampholder with a slotted arrangement for segregating the lead-in wires o'f the several coinpressible discs for facilitating the Wiring of the lampholder in a fluorescent fixture.

A further object of this invention is to provide a multiple fluorescent lampholder having a molded plastic base with parallel ribs in cooperation with the mounting brackets to insure the pro-per positioning of the mounting brackets with respect to the back surface of the lampholder.

The present invention incorporates a molded plastic base and a metal cover plate for the back to form the hollow housing. The use of -a plastic base makes itpossible to take advantage of an entirely new system for supporting and guiding the compressible discs which are used in turn to support the terminals of the lamp ends. Each disc is mounted in a lamp-receiving chamber formed in the molded base. A pair of opposed grooves are formed in the side walls of the chamber for receiving a mating pair of ears that extend from the sides of the disc and slide Within the said grooves. The grooves not only guide the disc in its movement Within the chamber, but each groove receives a coil spring that is seated against the ear of the disc and engages the back cover plate of the housing. Another important improvement is that the top wall of the base is provided with a slot that communicates with a pair of wire-receiving openings in the front face of the base so that the lead-in wires from each disc may be segregated from the others to facilitate the wiring of the lampholder in a fluorescent fixture. Another contribution is the use of parallel ribs molded within the interior of the chambers for guiding the discs in a straight line motion. These ribs provide minimum bearing areas with lines of contact between the discs and the complementary chambers to prevent binding or jamming of the discs. Similar ribs are used on the top surface of the molded base so that the mounting brackets that are fastened to the base will be exactlyperpendicular to theback surface of the lampholder.

My invention will be better understood from .the folice '2 lowing description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

FIGURE 1 is a front elevational view of a two lamp fluorescent lampholder embodying my invention for use with bi-pin lamps.

FIGURE 2 is an exploded View of the lampholder of FIGURE 1, showing in detail the several parts which are used in the practice of this invention as well as the details of construction.

FIGURE 3 is a back elevational view of the molded base of the lampholder of FIGURE 1 with the right-hand compressible disc in place and the insulating plate member shown in dotted lines.

Referring in detail to the drawing and in particular to the exploded view of FIGURE 2, a preferred embodiment of the lampholder of this invention comprises a hollow housing formed by a recessed base 11 of molded plastic such as urea formaldehyde resins, and a back cover plate 12 of zinc plated sheet steel. The molded base 11 has a general box-like construction with a front face 13, top and bottom walls 14 and 15, side walls 16 and an open back wall 17, as is best seen in FIGURE 3. It will be well understood by those skilled in this art that while the drawing shows a two lamp fluorescent lampholder, the same invention could .be adapted to produce a three lamp or four lamp type "of multiple compressible lamp.- holder. 7

The front face 13 of the lampholder has a circular opening 18 at each side and these openings are separated by a slanted surface 19 that extends inwardly of the front surface from the .top'to the bottom. When multiple lampholders are used in fixtures, the fixtures are often 'arranged in a continuous line so that a lampholder of one fixture will be back-to-back with a lampholder of an adjacent fixture. This slanted surface 19 results from a cutting away of the material of the front face to allow for a better diffusion of the light emitted from the lamp and a reduction in the dark areas between fixtures. Each opening 18 in the front face of the base communicates with a cylindrical chamber 22 that extends to the back cover plate 12. A movable disc 23 of insulating material is arranged in each chamber 22 for supporting one end of a fluorescent lamp (not shown). Each disc 23 is shown with two small apertures 24 that are spaced from each other and are adapted to receive the pins of a bipin lamp. Interchangeable discs similar to disc23 could, of course, be used instead to support a slimline lamp or a rapid start lamp with recessed terminals. For the sake of brevity, the present invention will be described with relation to a lampholder for birpin lamps.

Each disc 23 must be guided in the chamber 22.so that it will not turn, and the disc must be spring-biased toward the front face of the lampholder to normally close the opening 18 in a manner shown in FIGURE 1. Looking at the back of the base 11 in FIGURE 3, it will be noticed that each chamber 22 is provided with a pair of diametrically opposed cylindrical grooves 25. Each disc 23 has a pair of opposed cars 26 that slide in the.grooves 25. The cars 26 of the discs also serve as spring seats for a pair of double conical coil springs 27, as best seen .in.FIGURE 2. This type of spring is used because it may be compressed to the smallestdimension for a given strength of spring. Hence, the depth of this lampholder from front to back may be held to a minimum. Each groove 25 'has a restricted throat 28 that closely engages the car 26 where it is attached to the side of the disc 23. This restricted throat serves to confine the .coil springs 27 andprevent them from slipping out of position. Additional side projections 30 are formed on each disc at equally spaced distances from the ears 26 for assisting 3 the disc in its straight line movement within the chamber 22. These side projections 3d are adapted to fit Within mating 'guideways 31 formed in the side Walls of the chamber 22 as is clearly seen in FIGURE 3. Contact blades 32 are fastened by means of screws 33 to the back side of each disc 23 as is clearlyseen in FIGURE 3. The free end of each contact blade 32 overlies the inner end of the aperture 24 of the disc for making electrical connection with one of the two pins of a bi-pin lamp that protrude through the apertures 24. The fixed or terminal end of each contact blade 32 has bendable tabs 34 which are crimped over the bare strands of a lead wire 35.

In order to segregate the lead wires of the two discs 23, a special slotted feature is created at the center of'the top portion of the base 11. First, there is a vertical slot 37 in the top wall 14 of the base thatextends from the front to the back of the base. This slot 37 communicates With a pair of snubbing notches 38 that is arranged in the front face 13 of the base. There is a snubbing notch 38 arranged at each side of the vertical slot 37 so that the two lead wires 35 of each movable disc 23 may be yanked through the slot 37 from the back and into the nearest snubbing notch 38 The passageway 39'. connecting the vertical slot 37 with the snubbing notch has been made slightly smaller than the diameter of each lead wire so that a slight force is necessary to pull the lead wires into the notch.

Looking at the exploded view of FIGURE 2, there is shown an insulating plate member 40 with its side edges cut down from the sides of the back plate 12 so as not to engage the coil springs 27. In order to gain a better understanding of the relative size and shape of the plate 40 with respect to the back wall 17 of the base 11, the plate 40 is shown in dotted lines in FIGURE 3. This insulating plate 40 is considered necessary in order to insulate the contact blades 32 from the metallic back cover 12 under extreme conditions when the discs 23 are depressed completely within the chamber 22 of the base 11.

Continuing to examine the interior of the base 11 in FIGURE 3, attention is directed to the reinforcing ribs 42 and 43 which strengthen the sides of the cylindrical chambers 22 so that thin sections of material may be used to conserve the amount of molding compound. The back cover plate 12 has a rim 44 that extends along the sides and bottom portion of the cover. This rim 44 is designed to engage around the sides and bottom of the base 11 and it has a pair of lanced tabs 45 that engage behind shoulders 46 of the base as seen in FIGURE 1 to hold the lower end of the cover plate 12 onto the base. Fastening screws 47 are provided to extend through openings 48 in the top portion of the cover 12 and be threaded into tapped openings 49 of the base 11 as seen in FIGURE 3. Steel mounting brackets 50 are designed to fit onto the top wall 14 of the base for supporting the lampholder in a fluorescent fixture. Each bracket 50 has a side plate 51 that extends down along the side of a portion of the top wall for steadying the bracket in place. On the opposite side of the bracket there is a side-turned lip 52 that fits into an undercut portion 53 of the top wall of the base as best seen in FIGURE 3. The back portion of each bracket 50 has a down-turned plate (not shown) with an opening that overlies the tapped opening 49 of the base. Hence, each fastening screw 47 that attaches the back cover 12 to the base also extends through a back plate of one of the mounting brackets so that both brackets are rigidly connected to the housing formed by the molded base and the metal back cover.

It is of primary importance to insure that the movable discs 23 move in a straight line as they are forced inwardly of the base against the springs 27. .This is insured by the fact that a series of parallel ribs 55 are molded along the inner surface of each chamber 22 and are in line contact with the sides of the disc 23. This 4 permits the cylindrical chamber 22 to be made of a frusto-conical shape with the smallest end at the opening 18 in the front face 13 of the base. This frusto-conical shape is of importancein the molding operation as it permits the easy separation of the force of the mold from the cavity while it retains the necessary feature of a straight line motion for the discs. Similar parallel ribs 56 are formed on the top wall 14 of the base and under the horizontal portion of the mounting bracket 54% to insure that the bracket is mounted perpendicularly to the back surface of the lampholder. This is necessary because the outer periphery of the base 11'; namely, the top wall 14, bottom wall 15 and side walls 16 are tapered outwardly from the front face 1'3. 7 v

Having described above my invention of a novel multiple lampholder, it will be readily apparent to those skilled in this art' that I have reduced the cost of manufacture of such lampholders by adopting a molded plastic base which is not subject to corrosive atmospheres. This one step has enabled many important improvements to be made in such lampholders because the design of the lampholder is no longer dictated by the limitations inrposed by the stamping method of forming the hollow base. Molded products can be'made of many intricate shapes. As a result, I have been able to reduce the number of parts that make up a complete lampholder and have created a new family of such lampholders for use with all of the dilferent types of fluorescent lamps such as bi-pin, slimline and high output rapid start lamps. Three obvious advantages of a plastic lampholder are, first, that it may be made of an insulating material that can be used to directly support an electrical conducting member such as a contact. Secondly, such plastic materials are non-corrosive and will have a longer useful life under all atmospheric conditions. Thirdly, the snubbing notches 38 are formed in the molded base rather than in a metal housing to reduce the danger of cutting the insulation of the lead wires and causing a short circuit and possibly a fire hazard.

Modifications of this invention will occur to those skilled in this art and it is to be understood, therefore, that this invention is not limited to the particular embodiments disclosed but that it is intended to cover all modifications which are within the true spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

'l. A multiple fluorescent lampholder comprising a hollow housing with at least two similar lamp-receiving chambers having openings in the front face of the hous ing, a movable disc in each chamber, each disc supporting at least one contact member, at least one aperture formed in each of said discs so that the contact members of the discs may engage contacts of the lamps, a lead wire fastened to the contact member of each disc, the top wall of the lampholder housing containing a slot that opens into the top and back of the housing and communicates with a pair of wire-receiving openings in the front face of the housing, each of the openings being on an opposite side of the said slot and having a narrow mouth communicating with the said slot, the mouth being slightly smaller than the diameter of one of the lead wires so that the lead wire extending from each disc may be pulled through the slot and retained in the related wirereceiving opening to separate the wires for identification purposes.

2. A multiple fluorescent lampholder comprising a hollow housing with a recessed base of molded plastic material and a cover member, at least two similar lamp-receiving chambers having openings in the front face of the housing, and lamp supporting discs movably mounted in each chamber, the top Wall of the base including a central slot, a lead wire-receiving opening in the front face of the housing disposed at each side of the slot, said slot communicating with said openings through narrow mouth areas that are each of a width slightly less than the diameter of lead wires extending from said discs and adapted to be connected to lamp-engaging contacts thereon, whereby said lead wires may be pulled through the slot from the back of the housing and confined within the closest wire-receiving opening for identification purposes.

3. A multiple fluorescent lampholder comprising a hollow housing formed by a recessed base member and a back cover member, the base member having at least two similar lamp-receiving chambers that open into the front face of the base member, a movable disc in each cham her for supporting a lamp therein, each disc supporting at least one contact for making electrical connection with a lamp, and a lead wire joined with each said contact, the top wall of the base member containing a centrally located slot that communicates with a wire-receiving opening at either side of the slot, the said openings being in the front face of the base member so that the lead Wires may be pulled through the said slot and into the closest wire-receiving opening, the area between the said slot and each of said openings being of a width slightly less than the diameter of the lead wires so as to prevent the inadvertent removal of the wires from the said openings.

4. A fluorescent lampholder comprising a hollow housing with a recessed base and a back cover member, said base being of one-piece construction and formed from plastic material, at least one lamp-receiving chamber in said base that opens intothe front face of the base, said chamber being of generally frusto-conical shape, the end of the chamber having the smallest diameter being adjacent the front face of the base, and a series of spaced ribs formed in said chamber and extending longitudinally thereof, the innermost edges of the ribs being parallel to the longitudinal axis of the chamber from front to back thereof, said insulating base being formed of moldable material, and said frusto-conical shaped chamber providing for ease of separation from a mold during its fabrication, the thickness of said ribs being small in comparison with the size of the frusto-conical surface of the chamber, an insulating disc arranged in the chamber for supporting a lamp end, said disc being guided for straight line movement in the chamber by the ribs, the disc and side walls of the chamber having a complementary ear and groove means for preventing rotation of said disc during the movement thereof, and spring means located within the housing to bias the disc toward the front face of the base.

5. A multiple fluorescent lampholder comprising a hollow housing with a recessed base and a back cover member, said base being of one piece construction and formed from molded plastic material, at least two similar lampreceiving chambers in said base that open into the front face of the base, each of said chambers being of generally frusto-conical shape, the end of the chamber having the smallest diameter being adjacent the front face of the base, a series of spaced ribs formed in each chamber and extending longitudinally thereof, the innermost edges of the ribs being parallel to the longitudinal axis of the chamber, a movable disc in each chamber for supporting the end of a lamp, spring means located within the housing for biasing the discs to close the chambers from the front face of the base, a pair of removable mounting brackets fastened to a top wall of the base, a portion of the top wall of the base under each bracket having at least two parallel ribs formed thereon, said ribs being perpendicular to the back cover member of the housing and in engagement with respective brackets so that both mounting brackets are disposed in perpendicular alignment relative to said back cover member.

6. A fluorescent lampholder comprising a hollow housing formed with a recessed insulating base and a back cover plate, the base being of one-piece plastic material and having at least one lamp-receiving chamber with an opening in the front face, said chamber having a frustoconical shape with the end of smallest diameter being adjacent the front face of the base, and a series of longitudinally extending ribs formed in said chamber, the innermost edges of said ribs being parallel to the longitudinal axis of the chamber from front to back thereof, said insulating base being formed of mo-ldable material, and said frusto-conical shaped chamber providing for ease of separation from a mold during its fabrication, the thickness of said rib-s being small in comparison with the size of the frusto-conical surface of the chamber, an insulating disc arranged in the chamber for supporting a lamp end, said disc guided for straight-line movement in said chamber by said ribs, the disc having a pair of side ears that slide in a pair of complementary grooves in the side walls of the chamber, each groove having a restricted throat opening into the side surface of the chamber, and a coil spring confined in each groove by the throat and compressed between an ear of the disc and the back cover plate.

7. A multiple fluorescent lampholder as recited in claim 6 wherein the base includes top, bottom and side walls, at least one mounting bracket being fastened over the top wall of the base, the portion of the top wall underlying the bracket having at least two parallel ribs that extend from the front face to the back wall of the base so that the bracket will be seated on the ribs and lie perpendicularly to the back cover plate.

References Cited in the file of this patent UNITED STATES PATENTS 1,225,526 Thomas May 8, 1917 2,182,446 Nelson Dec. 5, 1939 2,199,219 Edwards et al. Apr. 30, 1940 2,635,169 Miller Apr. 14, 1953 2,728,057 ODonnell et a1 Dec. 20, 1955 FOREIGN PATENTS 474,328 Canada June 12, 1951 615,692 Great Britain Jan. 10, 1949 663,467 Great Britain Dec. 19, 1951 

